Terminal, radio communication method, base station, and system

ABSTRACT

A terminal is disclosed that includes a processor that, in case where frequency division duplex (FDD) is applied, controls a transmission of an uplink (UL) signal, in FDD, at a same timing as a UL transmission timing that is applied in time division duplex (TDD). The terminal also includes a receiver that receives a downlink control information (DCI), and a physical downlink shared channel (PDSCH) scheduled by the DCI. The terminal also includes a transmitter that transmits a HARQ-ACK in response to the PDSCH. The reception of the DCI and the transmission of the HARQ-ACK are allowed within one slot. In other aspects, a radio communication method, a base station, and a system are also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 16/086,767, filed on Sep. 20, 2018, which is anational phase application of PCT/JP2017/011099, filed on Mar. 21, 2017,which claims priority to Japanese Patent Application No. 2016-059128,filed on Mar. 23, 2016. The contents of these applications are herebyincorporated by reference in their entirety.

TECHNICAL FIELD

The present invention relates to a a terminal, a radio communicationmethod, a base station, and a system in a next-generation mobilecommunication system.

BACKGROUND ART

In the UMTS (Universal Mobile Telecommunications System) network, thespecifications of long term evolution (LTE) have been drafted for thepurpose of further increasing high speed data rates, providing lowerlatency and so on (see non-patent literature 1). In addition, successorsystems of LTE (referred to as, for example, “LTE-A (LTE-Advanced),”“FRA (Future Radio Access),” “5G (5th generation mobile communicationsystem),” “5G+(5G plus),” “New-RAT (Radio Access Technology)” and so on)are also under study for the purpose of achieving furtherbroadbandization and increased speed beyond LTE.

Existing LTE systems use control based on TDD (Time Division Duplex) andFDD (Frequency Division Duplex). For example, in TDD, whether eachsubframe in a radio frame is used in the uplink (“UL”) or in thedownlink (“DL”) is determined strictly based on UL/DL configurations.

CITATION LIST Non-Patent Literature

Non-Patent Literature 1: 3GPP TS 36.300 “Evolved Universal TerrestrialRadio Access (E-UTRA) and Evolved Universal Terrestrial Radio AccessNetwork (E-UTRAN); Overall Description; Stage 2”

SUMMARY OF INVENTION Technical Problem

Now, for future radio communication systems such as LTE Rel. 13 andlater versions (for example, 5G), radio frames (also referred to as“lean radio frames”) to provide good future scalability and excellentpower saving performance are under study. Lean radio frames are based onthe assumption of using subframes with no predetermined use (forexample, the direction in communication such as DL or UL, the type andformat of signals such as data, reference signals, sounding and feedbackinformation, and so on), except for some subframes (dynamic subframeutilization).

A study is in progress to design future radio communication systems thatemploy dynamic subframe utilization, based on time division duplex(TDD), which switches between DL communication and UL communication inthe same frequency band, over time. Meanwhile, future radiocommunication systems are also expected to support frequency divisionduplex (FDD), in which DL communication and UL communication areperformed in different frequency bands.

However, if the FDD communication scheme in existing LTE systems isapplied to TDD-based future radio communication systems on an as-isbasis, there is a fear that dynamic subframe utilization offers onlylimited advantages.

The present invention has been made in view of the above, and it istherefore an object of the present invention to provide a user terminal,a radio base station and a radio communication method, whereby, evenwhen FDD is used in future radio communication systems, the advantagesof dynamic subframe utilization can be achieved.

Solution to Problem

According to one aspect of the present invention, a user terminal has areceiving section that receives a downlink (DL) signal, a transmissionsection that transmits an uplink (UL) signal, and a control section thatcontrols the receipt of the DL signal and/or the transmission of the ULsignal in frequency division duplex (FDD), which use differentfrequencies, to the same timing as the receipt of the DL signal and/orthe transmission of the UL signal in time division duplex (TDD), whichuse the same frequency.

Advantageous Effects of Invention

According to the present invention, it is possible to achieve theadvantages of dynamic subframe utilization even when FDD is used infuture radio communication systems.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram to show an example of the format of lean radioframes;

FIG. 2 is a diagram to show an example of the format of lean radioframes;

FIGS. 3A and 3B are diagrams to show examples of DL communicationcontrol in TDD;

FIGS. 4A and 4B are diagrams to show examples of UL communicationcontrol in TDD;

FIGS. 5A to 5C are diagrams to show examples of sounding control in TDD;

FIGS. 6A to 6C are diagrams to show examples of DL communication controlaccording to a first aspect of the present invention;

FIGS. 7A and 7B are diagrams to show examples of signal feedback controlaccording to a first aspect of the present invention;

FIGS. 8A and 8B are diagrams to show examples of UL communicationcontrol according to the second aspect;

FIGS. 9A and 9B are diagrams to show other examples of UL communicationcontrol according to the second aspect;

FIG. 10 is a diagram to show an example of unused resources in FDD;

FIGS. 11A and 11B are diagrams to show examples of DL scheduling controlaccording to a third aspect of the present invention;

FIGS. 12A to 12C are diagrams to show detailed examples of DL schedulingcontrol according to the third aspect;

FIGS. 13A and 13B are diagrams to show examples of UL scheduling controlaccording to the third aspect;

FIGS. 14A and 14B are diagrams to show detailed examples of ULscheduling control according to the third aspect;

FIGS. 15A and 15B are diagrams to show other detailed examples of ULscheduling control according to the third aspect;

FIG. 16 is a diagram to show an example of a schematic structure of aradio communication system according to the present embodiment;

FIG. 17 is a diagram to show an example of an overall structure of aradio base station according to the present embodiment;

FIG. 18 is a diagram to show an example of a functional structure of aradio base station according to the present embodiment;

FIG. 19 is a diagram to show an example of an overall structure of auser terminal according to the present embodiment;

FIG. 20 is a diagram to show an example of a functional structure of auser terminal according to the present embodiment; and

FIG. 21 is a diagram to show an example of a hardware structure of aradio base station and a user terminal according to the presentembodiment.

DESCRIPTION OF EMBODIMENTS

An example of a communication method to use lean radio frames (forexample, 5G), for future radio communication systems such as LTE Rel. 13and later versions, will be described below with reference to FIG. 1 andFIG. 2. FIG. 1 is a diagram to show an example of the format of leanradio frames. As shown in FIG. 1, lean radio frames have a predeterminedtime duration (for example, five to forty ms). A lean radio frame iscomprised of a plurality of subframes, where each subframe has apredetermined time duration (for example, 0.125 ms, 0.25 ms, 1 ms,etc.).

Subframes in lean radio frames have a shorter time duration than thesubframes of existing LTE systems (LTE Rel. 8 to 12). As a result ofthis, subframes in lean radio frames can be transmitted and received ina short time, compared to existing LTE systems.

Lean radio frames are comprised of subframes with a predetermined use(also referred to as “fixed subframes”) and subframes with nopredetermined use (also referred to as “dynamic subframes,” “flexiblesubframes,” “dynamically utilized subframes” and so on).

In a lean radio frame, the timing of a fixed subframe may be determinedin advance (for example, subframe #0, subframe #5, etc.), or may beconfigured via higher layer signaling such as RRC (Radio ResourceControl) signaling, or via broadcast signaling. Furthermore, fixedsubframes may be provided in varying timings, on a per cell basis (thatis, the offset value may be determined per cell). For example, referringto FIG. 1, fixed subframes (fixed DL subframes), which are configured inadvance as DL subframes, are provided in a predetermined cycle (whichis, for example, five ms or more).

Note that multiple fixed DL subframes may be configured in a lean radioframe. In this case, fixed DL subframes may be mapped so as toconcentrate at a specific time within a lean radio frame (for example,in a specific period of two ms within a cycle of ten ms), so that it ispossible to make the cycle of fixed DL subframes longer, and reduceenergy consumption in, for example, radio base stations and userterminals that perform transmission/receipt using fixed DL subframes.

Meanwhile, by mapping fixed DL subframes so as to be distributed withina lean radio frame, it is possible to make the cycle of fixed DLsubframes shorter, which can, for example, make it easier to buildquality connections with user terminals that move at high speeds. Thelocations and the cycle of time resources for fixed DL subframes may beselected by a radio base station from a plurality of combinations thatare prepared in advance, and a possible combination may be detected by auser terminal on a blind basis, or the locations and the cycle of timeresources for fixed DL subframes may be reported from the radio basestation to the user terminal via broadcast signals, RRC signaling and soon.

Also, although not shown in the drawings, fixed subframes (fixed ULsubframes) that are configured in advance as UL subframes may beprovided in lean radio frames. In these fixed UL subframes, resourcesfor the signals (for example, random access preambles) for initialaccess (stand-alone operation) to cells using lean radio frames may bereserved.

Also, the use of dynamic subframes may be designated by a DL controlsignal (also referred to as a “DL control channel,” an “L1/L2 controlsignal,” an “L1/L2 control channel” and so on) in each dynamic subframe(dynamic assignment), or may be designated by fixed DL subframes(semi-dynamic assignment). Thus, when dynamic subframe utilization isemployed, the use of subframes may be specified dynamically on a persubframe basis, or may be specified semi-dynamically for everypredetermined number of subframes (for example, every multiple dynamicsubframes between fixed DL subframes).

FIG. 2 is a diagram to show examples of the formats of fixed DLsubframes and dynamic subframes. Note that the formats of fixed DLsubframes and dynamic subframes shown in FIG. 2 are simply examples, andthose shown in FIG. 2 are by no means limiting.

As shown in FIG. 2, fixed DL subframes are used to transmit signals forcell discovery (detection), synchronization, measurements (for example,RRM (Radio Resource Management) measurements including RSRP (ReferenceSignal Received Power) measurements), mobility control, initial accesscontrol, and so on.

The signals to be transmitted in fixed DL subframe may be, for example,at least one of a detection signal, a detection measurement signal, ameasurement signal, a mobility measurement signal, a discovery referencesignal (DRS), a discovery signal (DS), synchronization signals (PSS(Primary Synchronization Signal) and/or SSS (Secondary SynchronizationSignal)), a broadcast signal (broadcast information (MIB (MasterInformation Block) and/or system information (SIBs (System InformationBlocks)) and a channel state information reference signal (CSI-RS).

Also, the signals to be transmitted in fixed DL subframes may bedesignated by the DL control signals of the fixed DL subframes, may bedetermined in advance, or may be configured via RRC signaling. If thesignals to be transmitted in fixed DL subframe are designated by DLcontrol signals, a radio base station can command a user terminal toreceive DL data, DL sounding RSs and so on, in fixed DL subframes(scheduling).

Here, when DL control signals of different roles are multiplexed overthe same DL control channel, for example, different IDs (RNTIs and/orthe like) can be applied to the DL control signals of respective rolesto mask the CRC (Cyclic Redundancy Check). In this case, in fixed DLsubframes, the information to be reported in common to a plurality ofuser terminals (for example, a broadcast signal or a broadcast-basedsignal) can be scheduled, information about the subframe format ofdynamic subframes (for example, information about the direction ofcommunication in the data channel) can be reported, and DL data and theDL sounding RS can be transmitted and scheduled using resources that areleft after reporting information about the position of the fixed ULsubframe, and so on.

On the other hand, the dynamic subframes can be used to transmit thesignals designated by the DL control signals of the dynamic subframes(or the fixed DL subframes), such as DL and/or UL (hereinafter referredto as “DL/UL”) data, DL/UL sounding, feedback signals in response touplink control information (UCI), random access preambles, and so on.

Furthermore, in dynamic subframes, assignment may be performed so thattransmission/receipt control (scheduling) is completed within dynamicsubframes, in order to enable short-time communication. This type ofassignment is also referred to as “self-contained assignment.”Subframes, in which self-contained assignment is performed, may bereferred to as “self-containment subframes.” Self-contained subframesmay be referred to as “self-contained TTIs” or “self-contained symbolsets,” or other names may be applied as well.

Furthermore, in FIG. 2, the DL control signals aretime-division-multiplexed (TDM: Time Division Multiplexing) with othersignals (for example, with a data signal and other signals), but this isby no means limiting. The DL control signals may betime-division-multiplexed (TDM) and/or frequency-division-multiplexed(FDM: Frequency Division Multiplexing) with other signals, or may beembedded in data signals (or placed in some of the resource elements(RE) of the symbols assigned to the data signals).

A study is in progress to design future radio communication systems thatemploy the above-described dynamic subframe utilization based on TDD.With reference to FIGS. 3A, 3B, 4A, 4B, 5A, 5B, and 5C, examples ofcommunication using TDD-based dynamic subframes will be described.

FIGS. 3A and 3B provide diagrams to show examples of DL communicationcontrol in TDD. As shown in FIG. 3A, a DL control signal (for example, aDL assignment) assigns (schedules) DL data signals in the same subframeas that of the DL control signal, or in a plurality of subframes afterthat subframe.

In FIG. 3A, the number of subframes (also referred to as “TTI duration”)in which DL data signals are assigned may be indicated explicitly by theDL control signal, may be indicated implicitly by at least one of thetransport block size, the number of resource blocks (PRBs: PhysicalResource Blocks) assigned to the DL data signals, and so on.

Furthermore, as shown in FIG. 3B, a feedback signal (for example, anHARQ-ACK: (Hybrid Automatic Repeat reQuest-Acknowledgment), etc.) inresponse to a DL data signal may be transmitted in the same subframe asthat of the DL data signal, or may be transmitted in a subsequentsubframe. As shown in the bottom diagram in FIG. 3B, a feedback signalin response to the DL data signals of a plurality of different subframesmay be multiplexed.

As shown in the top diagram in FIG. 3B, when a DL control signal thatassigns a DL data signal, this DL data signal and a feedback signal inresponse to this DL data signal are included in the same subframe(self-contained subframe), it is possible to realize feedback withultra-low delay of one ms or less, for example, so that the latency canbe reduced.

FIGS. 4A and 4B provide diagrams to show examples of UL communicationcontrol in TDD. As shown in FIG. 4A, a DL control signal (for example, aUL grant) may assign (schedule) a UL data signal in the same subframe asthat of the DL control signal, or in a plurality of subframes after thatsubframe.

Alternatively, as shown in FIG. 4B, a DL control signal (for example, aUL grant) may assign (schedule) a UL data signal in at least onesubframe after the same subframe of this DL control signal. For example,in FIG. 4B, a UL data signal is assigned in the next and a latersubframe of the subframe of the DL control signal.

In FIGS. 4A and 4B, the number of subframes (also referred to as the“TTI duration”) in which UL data signals are assigned may be indicatedexplicitly by the DL control signal, or may be indicated implicitlybased on at least one of the transport block size, the number of PRBsassigned to the UL data signals, and so on.

Also, although not shown in the drawings, a feedback signal (forexample, an HARQ-ACK, etc.) in response to a UL data signal may betransmitted in the same subframe as that of the UL data signal, or maybe transmitted in a subsequent subframe. Furthermore, feedback signalsin response to the UL data signals in a plurality of different subframesmay be multiplexed.

FIGS. 5A, 5B, and 5C provide diagrams to show examples of soundingcontrol in TDD. FIGS. 5A and 5B show examples of measuring and reportingDL channel states using a DL sounding reference signal (RS). The DLsounding RS is a signal for measuring DL channel states, and may bereferred to as the “CSI-RS,” and/or the like.

As shown in FIGS. 5A and 5B, a DL control signal may assign (schedule)the DL sounding RS in the same subframe as that of the DL controlsignal. In FIGS. 5A and 5B, CSI that is measured based on this DLsounding RS is fed back using resources specified by a DL control signalthat is different from the above DL control signal for assigning the DLsounding RS.

Note that the DL sounding RS may be assigned by a DL control signal (forexample, a DL assignment) that assigns a DL data signal. In this case,the DL sounding RS and the DL data signal can be multiplexed in the samesubframe. Alternatively, the DL sounding RS may be assigned by a DLcontrol signal for DL sounding.

Furthermore, although not shown in the drawings, the above DL controlsignal for assigning the DL sounding RS may specify the resources forfeeding back the CSI measured based on this DL sounding RS. In thiscase, the CSI above may be fed back in the same subframe as that of theDL sounding RS, or in a subsequent subframe.

FIG. 5C shows an example of measuring UL channel states using a ULsounding RS. The UL sounding RS is a signal for measuring UL channelstates, and may be referred to as the “sounding reference signal (SRS)”and/or the like.

As shown in FIG. 5C, a DL control signal may assign (schedule) the ULsounding RS in the same subframe as that of the DL control signal. SinceCSI measurements using the UL sounding RS takes place in the radio basestation, CSI feedback from the user terminal is not necessary in the UL.

Note that the UL sounding RS may be assigned by a DL control signal (forexample, a UL grant) that assigns a UL data signal. In this case, the ULsounding RS and the UL data signal can be multiplexed in the samesubframe. Alternatively, the UL sounding RS may be assigned by a DLcontrol signal for UL sounding.

Thus, studies are in progress to design future radio communicationsystems that adopt dynamic subframe utilization, based on TDD.Meanwhile, future radio communication systems are also expected tosupport FDD. However, if the FDD communication scheme in existing LTEsystems is applied to TDD-based future radio communication systems on anas-is basis, there is a fear that dynamic subframe utilization offersonly limited advantages.

So, the present inventors have studied ways to achieve the advantages ofTDD-based dynamic subframe utilization even when FDD is used in futureradio communication systems, and arrived at the present invention. To bemore specific, the present inventors have come up with the idea ofcontrolling the transmission of DL signals and/or the receipt of ULsignals in FDD, which use different frequencies, to the same timing asthe transmission of DL signals and/or the receipt of UL signals in TDD,which use the same frequency, as one aspect of the present invention.

Now, the radio communication method according to one embodiment of thepresent invention will be described below. Note that, in the presentembodiment, subframes may be one ms, which is the same as in existingLTE systems, or may be shorter than one ms, longer than one ms, and soon. Furthermore, the duration of each symbol in subframes may have thesame as in existing LTE systems, may be shorter than in existing LTEsystems, or may be longer than in existing LTE systems. Furthermore, thenumber of symbols in a subframe may be the same as or different fromthat in existing LTE systems.

Furthermore, a subframe may be referred to as a “transmission timeinterval (TTI).” A subframe (one ms), if shorter than one ms, may bereferred to as a “short subframe,” “short TTI,” and so on. Meanwhile, asubframe from existing LTE systems is also referred to as an “LTEsubframe,” a “normal TTI,” a “long TTI,” and so on.

Furthermore, the DL communication control and/or UL communicationcontrol according to the present embodiment may be applied to theabove-described dynamic subframes in lean radio frames. That is to say,subframes in the following description may refer to the above-describeddynamic subframes in lean radio frames, or may be fixed DL subframes.Furthermore, the UL/DL data in the drawings described below may includeUL/DL sounding reference signals.

(First Aspect)

Based on a first aspect of the present invention, DL communicationcontrol will be described. According to the first aspect, even in FDD inwhich DL communication and UL communication are performed usingdifferent frequencies, control that relates to DL communication (forexample, DL scheduling) is exerted in the same timing as in TDD in whichDL communication and UL communication are switched over time in the samefrequency.

To be more specific, according to the first aspect, a feedback signal(for example, an HARQ-ACK) in response to a DL data signal istransmitted at the same timing as a TDD feedback signal, which istransmitted using the same frequency as that of the DL data signal, byusing a different frequency from that of the DL data signal.

FIGS. 6A, 6B, and 6C provide diagrams to show examples of DLcommunication control according to the first aspect. As shown in FIGS.6A, 6B, and 6C, in TDD, DL communication and UL communication areswitched over time in the same frequency band. Meanwhile, in FDD, DLcommunication and UL communication are performed in different frequencybands.

As shown in FIG. 6A, when FDD is used, in a given subframe, the userterminal receives a DL control signal using the frequency for DL (firstfrequency) (hereinafter referred to as the “DL frequency”), and receivesa DL data signal assigned in the same subframe as that of the DL controlsignal.

The user terminal transmits a feedback signal in response to the DL datasignal in the same timing as that of a feedback signal in TDD, by usingthe frequency for UL (second frequency) (hereinafter referred to as the“UL frequency”). Here, the feedback signal may be transmitted in thesame subframe as that of the DL data signal (FIG. 6A), or may betransmitted in a subsequent subframe (FIG. 6B).

Also, referring to FIGS. 6A and 6B, when TDD is used, a guard period isprovided between the DL period in which the DL control signal and the DLdata signal are received, and the UL period in which the feedback signalis transmitted. When FDD is used, the feedback signal is transmittedafter the guard period, using the UL frequency.

Note that, in FIGS. 6A and 6B, a DL control signal that is transmittedin the DL frequency may assign DL data signals over a plurality ofsubframes (see FIG. 3A). The number of subframes (also referred to as“TTI duration”) where DL data signals are assigned may be indicatedexplicitly by the DL control signal, or may be indicated implicitly byat least one of the transport block size, the number of PRBs assigned tothe DL data signals, and so on.

Also, as shown in FIG. 6C, when the user terminal receives a pluralityof DL data signals, assigned by DL control signals in a plurality ofsubframes, respectively, in the DL frequency, the user terminal maymultiplex the feedback signals in response to these multiple DL datasignals over the same subframe, and transmit this in the UL frequency.

FIGS. 7A and 7B provide diagrams to show examples of feedback signalcontrol according to the first aspect. In TDD, a feedback signal inresponse to a DL data signal may be transmitted (implicitly) withoutexplicit assignment (grant), or may be transmitted based on explicitassignment.

As shown in FIG. 7A, when FDD is used, the user terminal may transmit afeedback signal in response to a DL data signal, received via a DLfrequency in a given subframe, by using UL-frequency feedback resourcesthat are implicitly assigned. The feedback resources may be determinedbased on, for example, the control channel elements (CCEs) thatconstitute the DL control signal. Note that these feedback resources maybe provided in the same subframe as that of the DL data signal, or maybe provided in a subsequent subframe.

As shown in FIG. 7B, in an FDD-based dynamic subframe, the user terminalmay transmit a feedback signal in response to a DL data signal, receivedvia a DL frequency, by using UL-frequency feedback resources that areassigned explicitly. In FIG. 7B, for example, feedback resources areassigned by a DL control signal. Note that this DL control signal may bea UL grant for assigning a UL data signal. Furthermore, in FIG. 7B, thisDL control signal is transmitted two subframes after a DL data signal,but this is by no means limiting, and the DL control signal may betransmitted in any subframe after the DL data signal.

As described above, according to the first aspect of the presentinvention, even when FDD is used, DL communication (for example, receiptof DL data signals, transmission of feedback signals, etc.) iscontrolled in the same timing as in TDD. Therefore, even when FDD isused in future radio communication systems, it is possible to achievethe advantages of dynamic subframe utilization. Also, even when the userterminal to communicate in this FDD carrier is not capable offull-duplex (which is simultaneous DL receipt and UL transmission) (thatis, when the user terminal is only capable of half-duplex), dynamicsubframes can be employed by applying the same control as in TDD, sothat it is not necessary to apply a plurality of different kinds ofscheduling control depending on the user terminal's capabilities, and itis possible to simplify the implementation of the scheduler in the basestation.

(Second Aspect)

Based on a second aspect of the present invention, UL communicationcontrol will be described. According to the second aspect, even in FDD,in which DL communication and UL communication are performed usingdifferent frequencies, control that relates to UL communication (such asUL scheduling) is exerted in the same timing as in TDD, in which DLcommunication and UL communication are switched over time in the samefrequency.

To be more specific, in the second aspect, a UL data signal that isscheduled by a DL control signal is transmitted in the same timing as aUL data signal in TDD, which is transmitted using the same frequency asthis DL control signal, by using a different frequency from that of thisDL signal.

FIGS. 8A and 8B provide diagrams to show examples of UL communicationcontrol according to the second aspect. As shown in FIGS. 8A and 8B,when FDD is used, in a given subframe, the user terminal receives a DLcontrol signal (for example, a UL grant) via a DL frequency. Based onthe scheduling (assignment) information contained in this DL controlsignal, the user terminal may transmit a UL data signal, in the subframecontaining this DL control signal or in a later subframe, using a ULfrequency.

For example, the user terminal may transmit a UL data signal in the samesubframe as that of the DL control signal, as shown in FIG. 8A, ortransmit UL data signals in a plurality of subframes after thissubframe, as shown in FIG. 8B.

Also, referring to FIGS. 8A and 8B, when TDD is used, a guard period isprovided between the DL period in which the DL control signal isreceived and the UL period in which the UL data signal is transmitted.When FDD is used, the UL data signal is transmitted after the guardperiod, using the UL frequency.

FIGS. 9A and 9B provide diagrams to show other examples of ULcommunication control according to the second aspect. As shown in FIGS.9A and 9B, when FDD is used, in a given subframe, the user terminal mayreceive a DL control signal, which is received in a DL frequency, andbased on the scheduling information contained in this DL control signal,the user terminal may transmit, by using a UL frequency, a UL datasignal in at least one subframe after the subframe in which the DLcontrol signal was contained.

For example, the user terminal may transmit a UL data signal in the nextsubframe of the DL control signal, as shown in FIG. 9A, or transmit ULcontrol signals in the next two subframes of the DL control signal, asshown in FIG. 9B. When TDD is used, DL control signals for other userterminals are transmitted in a predetermined number of symbols at thetop of a subframe, so UL data signals cannot be assigned here. On theother hand, in FDD, DL control signals for other user terminals aretransmitted in different frequencies than UL data signals, so that it ispossible to assign UL data signals at the beginning of subframes.

In FIGS. 8A, 8B, 9A, and 9B, the number of subframes (also referred toas the “TTI duration”) in which UL data signals are assigned may beindicated explicitly by the DL control signal, or may be indicatedimplicitly based on at least one of the transport block size, the numberof PRBs assigned to the UL data signals, and so on.

Also, although not shown in the drawings, a feedback signal (forexample, an HARQ-ACK, etc.) in response to a UL data signal may betransmitted in the same subframe as that of the UL data signal, or maybe transmitted in a subsequent subframe. Furthermore, feedback signalsin response to the UL data signals in a plurality of different subframesmay be multiplexed.

As described above, according to the second aspect of the presentinvention, even when FDD is used, UL communication (for example,transmission of UL data signals, transmission of feedback signals, etc.)is controlled in the same timing as in TDD. Therefore, even when FDD isused in future radio communication systems, it is possible to achievethe advantages of adopting dynamic subframe utilization. Also, even whenthe user terminal to communicate in this FDD carrier is not capable offull-duplex (which is simultaneous DL receipt and UL transmission) (thatis, when the user terminal is only capable of half-duplex), dynamicsubframes can be employed by applying the same control as in TDD, sothat it is not necessary to apply a plurality of different kinds ofscheduling control depending on the user terminal's capabilities, and itis possible to simplify the implementation of the scheduler in the basestation.

(Third Aspect)

Given that, in TDD, DL communication and UL communication are switchedover time in the same frequency band, and it follows that TDD is ahalf-duplex communication scheme, in which only one of transmission andreceipt can be performed at a given time. On the other hand, in FDD, DLcommunication and UL communication are performed in different frequencybands, and it follows that, depending on the capabilities of the userterminal, FDD can be a full-duplex communication scheme, in whichtransmission and receipt can be performed at the same time.

If the user terminal can adopt the full-duplex FDD communication scheme,as has been described earlier with the first and second aspects of thepresent invention, when DL communication and/or UL communication arecontrolled in the same way as when the half-duplex TDD communicationscheme is used, unused resources might increase, and the efficiency ofthe use of resources might decrease.

FIG. 10 is a diagram to show an example of unused resources in FDD. Asshown in FIG. 10, when the half-duplex TDD communication scheme isadopted, unused resources will not occur, except for the guard period(GP). On the other hand, when the full-duplex FDD communication schemeis used, in addition to the guard period, the UL frequency in the DLperiod in which DL signals are received and the DL frequency in the ULperiod in which UL signals are transmitted are not used either.

So, according to the third aspect, the UL frequency and/or DL frequencyresources that are unoccupied when the full-duplex FDD communicationscheme is used are also subject to scheduling. With the third aspect,the differences from the first and/or third aspects will be primarilydescribed.

Note that, in the following description, the UL frequency that isunoccupied in FDD may be scheduled for user terminals that use the DLfrequency, or may be scheduled for other user terminals. To be morespecific, in the UL frequency that is unoccupied in FDD, UL data signalsand/or UL sounding reference signals from user terminals that use the DLfrequency and/or other user terminals may be scheduled for transmission.

Similarly, the DL frequency that is unoccupied in FDD may be scheduledfor user terminals using the UL frequency, or may be scheduled for otheruser terminals. To be more specific, in the DL frequency that isunoccupied in FDD, DL data signals and/or DL sounding reference signalsfrom user terminals that use the UL frequency and/or other userterminals may be scheduled for receipt.

<DL Scheduling>

Based on the DL scheduling according to the third aspect, in at leastone of a DL period in which a DL data signal and a DL control signalthat schedules this DL data signal are transmitted/received using the DLfrequency, and a guard period in TDD, a UL data signal and/or a ULsounding reference signal (hereinafter referred to as “UL data/soundingreference signals”) are transmitted and received using the UL frequency.

Furthermore, in at least one of a UL period in which a feedback signalin response to the DL data signal is transmitted and received using theUL frequency, and the above guard period, a DL data signal and/or a DLsounding reference signal (hereinafter referred to as “DL data/soundingreference signals”) are transmitted and received using the DL frequency.

FIGS. 11A and 11B is a diagram to show an example of DL schedulingcontrol according to the third aspect. A DL control signal and a DL datasignal that is scheduled by this DL control signal may be received, anda feedback signal (for example, an HARQ-ACK) in response to this DL datasignal may be transmitted, all in the same subframe, as shown in FIG.11A, or in separate subframes, as shown in FIG. 11B.

Referring now to FIGS. 11A and 11B, in the DL period (DL) in which a DLcontrol signal and a DL data signal are transmitted and received usingthe DL frequency, and in the guard period (GP) in TDD, UL data/soundingreference signals are transmitted and received using the UL frequency.The UL data/sounding reference signals may be scheduled by the DLcontrol signal transmitted in the same subframe as that of the DL datasignal or in a preceding subframe, or may be configured by higher layersignaling (resources may be configured).

Also, referring to FIGS. 11A and 11B, in the UL period (UL), in which afeedback signal is transmitted and received using the UL frequency, DLdata/sounding reference signals are transmitted and received using theDL frequency. The DL data/sounding reference signals may be scheduled bythe DL control signal transmitted in the same subframe as that of the DLdata signal or in a preceding subframe, or may be configured by higherlayer signaling (resources may be configured).

FIGS. 12A, 12B, and 12C provide diagrams to show detailed examples of DLscheduling control according to the third aspect. As shown in FIG. 12A,the UL data/sounding reference signals transmitted and received usingthe UL frequency in the DL period in subframe n may be scheduled by theDL control signal (for example, a UL grant) of subframe n. In this case,the user terminal needs time to receive (decode) the DL control signal,and so the UL data/sounding reference signals cannot be assigned fromthe beginning of subframe n.

Therefore, as shown in FIG. 12A, the UL data/sounding reference signalsmay be scheduled, in the time period for receiving (decoding) the DLcontrol signal in subframe n, by the DL control signal of subframe n-1.For example, in FIG. 12A, the UL sounding reference signal may beassigned by the DL control signal of subframe n-1, and the UL datasignal may be assigned by the DL control signal of subframe n.

Meanwhile, cases might occur where the time period from the receipt of aDL control signal (for example, a UL grant) in subframe n to thetransmission of UL data/sounding reference signals cannot be made shortenough with respect to the subframe duration. In this case, as shown inFIG. 12B, the UL data/sounding reference signals transmitted andreceived using the UL frequency in the DL period of subframe n may bescheduled by the DL control signal (for example, a UL grant) of subframen-1.

Furthermore, as shown in FIG. 12C, the DL data/sounding referencesignals transmitted and received using the DL frequency in the guardperiod and the UL period of subframe n may be scheduled by the DLcontrol signal (for example, a UL grant) of subframe n. The schedulinginformation of the DL data/sounding reference signals may be included inthe DL data signal-assigning DL control signal in same subframe n, ormay be included in a DL control signal that is different from that DLcontrol signal. In the former case, a new bit field may be introduced inexisting DCI formats.

<UL Scheduling Control>

Based on the UL scheduling according to the third aspect, in at leastone of a DL period in which a DL control signal that schedules a UL datasignal is transmitted and received using the DL frequency, and a guardperiod in TDD, UL data/sounding reference signals are transmitted andreceived using the UL frequency.

Furthermore, DL data/sounding reference signals are transmitted andreceived using the DL frequency, in at least one of a UL period in whicha UL data signal is transmitted and received using the UL frequency, andthe above guard period.

FIGS. 13A and 13B provide diagrams to show examples of UL schedulingcontrol according to the third aspect. A DL control signal may bereceived, and a DL data signal that is scheduled by this DL controlsignal may be transmitted, all in the same subframe, as shown in FIG.13A, or in separate subframes, as shown in FIG. 13B.

Referring to FIGS. 13A and 13B, in the DL period (DL) in which a DLcontrol signal is transmitted and received using the DL frequency, andin the guard period (GP) in TDD, UL data/sounding reference signals aretransmitted and received using the UL frequency. The UL data/soundingreference signals may be scheduled by the DL control signal transmittedin the same subframe as that of the DL data signal or in a precedingsubframe, or may be configured by higher layer signaling (resources maybe configured).

Also, referring to FIGS. 13A and 13B, in the UL period (UL), in which aUL data signal is transmitted and received using the UL frequency, DLdata/sounding reference signals are transmitted and received using theDL frequency. The DL data/sounding reference signals may be scheduled bythe DL control signal transmitted in the same subframe as that of the DLdata signal or in a preceding subframe, or may be configured by higherlayer signaling (resources may be configured).

FIGS. 14A and 14B provide diagrams to show detailed examples of ULscheduling control according to the third aspect. As shown in FIG. 14A,the UL data/sounding reference signals transmitted in the UL period ofeach subframe may be scheduled by the DL control signal of the samesubframe. In this case, since the user terminal needs time to receive(decode) the DL control signal, and therefore the UL data/soundingreference signals cannot be assigned from the beginning of subframe n.

So, as shown in FIG. 14A, the DL control signal from the previoussubframe may schedule the UL data/sounding reference signals in the DLperiod in the next subframe and in the guard period. For example,referring to FIG. 14A, the UL sounding reference signal may be assignedby the DL control signal of subframe n-1, and the UL data signal may beassigned by the DL control signal of subframe n.

Meanwhile, cases might occur where the time period from the receipt of aDL control signal (for example, a UL grant) in each subframe to thetransmission of UL data/sounding reference signals cannot be made shortenough with respect to the subframe duration. In this case, as shown inFIG. 14B, the UL data/sounding reference signals in the next subframemay be scheduled by using the DL control signal (for example, a ULgrant) from the previous subframe. Note that, in FIGS. 14A and 14B, theDL control signal may be transmitted in a subframe that is one or moresubframes earlier.

FIGS. 15A and 15B provide diagrams to show other detailed examples of ULscheduling control according to the third aspect. The UL data/soundingreference signals transmitted and received using the UL frequency in theUL period of subframe n may be scheduled by the DL control signal in thesame subframe n, as shown in FIG. 15A, or scheduled by the DL controlsignal in previous subframe n-1, as shown in FIG. 15B.

In FIGS. 15A and 15B, in the UL period in subframe n, the DLdata/sounding reference signals may be transmitted and received usingthe DL frequency. The DL data/sounding reference signals may bescheduled by the DL control signal (for example, a UL grant) of subframen, as shown in FIGS. 15A and 15B.

The DL control signal may be a DL control signal for scheduling ULdata/sounding signals as shown in FIG. 15A, or may be another DL controlsignal for scheduling DL data/sounding signals, which is different fromthe above DL control signal, as shown in FIG. 15B.

(Radio Communication System)

Now, the structure of a radio communication system according to anembodiment of the present invention will be described below. In thisradio communication system, communication is performed using one or acombination of the radio communication methods according to the aboveaspects of the present invention.

FIG. 16 is a diagram to show an example of a schematic structure of aradio communication system according to the present embodiment. A radiocommunication system 1 can adopt carrier aggregation (CA) and/or dualconnectivity (DC) to group a plurality of fundamental frequency blocks(component carriers) into one, where the LTE system bandwidth (forexample, 20 MHz) constitutes one unit.

Note that the radio communication system 1 may be referred to as “LTE(Long Term Evolution),” “LTE-A (LTE-Advanced),” “LTE-B (LTE-Beyond),”“SUPER 3G,” “IMT-Advanced,” “4G (4th generation mobile communicationsystem),” “5G (5th generation mobile communication system),” “FRA(Future Radio Access),” “New-RAT (Radio Access Technology)” and so on,or may be seen as a system to implement these.

The radio communication system 1 shown in FIG. 16 includes a radio basestation 11 that forms a macro cell C1 of relatively a wide coverage, andradio base stations 12 (12 a to 12 c) that form small cells C2, whichare placed within the macro cell C1 and which are narrower than themacro cell C1. Also, user terminals 20 are placed in the macro cell C1and in each small cell C2.

The user terminals 20 can connect with both the radio base station 11and the radio base stations 12. The user terminals 20 may use the macrocell C1 and the small cells C2 at the same time by means of CA or DC.Furthermore, the user terminals 20 may apply CA or DC using a pluralityof cells (CCs) (for example, five or fewer CCs or six or more CCs).

Between the user terminals 20 and the radio base station 11,communication can be carried out using a carrier of a relatively lowfrequency band (for example, 2 GHz) and a narrow bandwidth (referred toas, for example, an “existing carrier,” a “legacy carrier” and so on).Meanwhile, between the user terminals 20 and the radio base stations 12,a carrier of a relatively high frequency band (for example, 3.5 GHz, 5GHz and so on) and a wide bandwidth may be used, or the same carrier asthat used in the radio base station 11 may be used. Note that thestructure of the frequency band for use in each radio base station is byno means limited to these.

A structure may be employed here in which wire connection (for example,means in compliance with the CPRI (Common Public Radio Interface) suchas optical fiber, the X2 interface and so on) or wireless connection isestablished between the radio base station 11 and the radio base station12 (or between two radio base stations 12).

The radio base station 11 and the radio base stations 12 are eachconnected with higher station apparatus 30, and are connected with acore network 40 via the higher station apparatus 30. Note that thehigher station apparatus 30 may be, for example, access gatewayapparatus, a radio network controller (RNC), a mobility managemententity (MME) and so on, but is by no means limited to these. Also, eachradio base station 12 may be connected with the higher station apparatus30 via the radio base station 11.

Note that the radio base station 11 is a radio base station having arelatively wide coverage, and may be referred to as a “macro basestation,” a “central node,” an “eNB (eNodeB),” a “transmitting/receivingpoint” and so on. Also, the radio base stations 12 are radio basestations having local coverages, and may be referred to as “small basestations,” “micro base stations,” “pico base stations,” “femto basestations,” “HeNBs (Home eNodeBs),” “RRHs (Remote Radio Heads),”“transmitting/receiving points” and so on. Hereinafter the radio basestations 11 and 12 will be collectively referred to as “radio basestations 10,” unless specified otherwise.

The user terminals 20 are terminals to support various communicationschemes such as LTE, LTE-A and so on, and may be either mobilecommunication terminals (mobile stations) or stationary communicationterminals (fixed stations).

In the radio communication system 1, as radio access schemes, orthogonalfrequency division multiple access (OFDMA) is applied to the downlink,and single-carrier frequency division multiple access (SC-FDMA) isapplied to the uplink.

OFDMA is a multi-carrier communication scheme to perform communicationby dividing a frequency bandwidth into a plurality of narrow frequencybandwidths (subcarriers) and mapping data to each subcarrier. SC-FDMA isa single-carrier communication scheme to mitigate interference betweenterminals by dividing the system bandwidth into bands formed with one orcontinuous resource blocks per terminal, and allowing a plurality ofterminals to use mutually different bands. Note that the uplink anddownlink radio access schemes are not limited to these combinations, andother radio access schemes may be used.

In the radio communication system 1, a downlink shared channel (PDSCH:Physical Downlink Shared CHannel), which is used by each user terminal20 on a shared basis, a broadcast channel (PBCH: Physical BroadcastCHannel), downlink L1/L2 control channels and so on are used as downlinkchannels. User data, higher layer control information and SIBs (SystemInformation Blocks) are communicated in the PDSCH. Also, the MIB (MasterInformation Block) is communicated in the PBCH.

The downlink L1/L2 control channels include a PDCCH (Physical DownlinkControl CHannel), an EPDCCH (Enhanced Physical Downlink ControlCHannel), a PCFICH (Physical Control Format Indicator CHannel), a PHICH(Physical Hybrid-ARQ Indicator CHannel) and so on. Downlink controlinformation (DCI), including PDSCH and PUSCH scheduling information, iscommunicated by the PDCCH. The number of OFDM symbols to use for thePDCCH is communicated by the PCFICH. Delivery acknowledgment information(also referred to as, for example, “retransmission control information,”“HARQ-ACKs,” “ACK/NACKs,” etc.) of HARQ (Hybrid Automatic RepeatreQuest) in response to the PUSCH is transmitted by the PHICH. TheEPDCCH is frequency-division-multiplexed with the PDSCH (downlink shareddata channel) and used to communicate DCI and so on, like the PDCCH.

In the radio communication system 1, an uplink shared channel (PUSCH:Physical Uplink Shared CHannel), which is used by each user terminal 20on a shared basis, an uplink control channel (PUCCH: Physical UplinkControl CHannel), a random access channel (PRACH: Physical Random AccessCHannel) and so on are used as uplink channels. User data and higherlayer control information are communicated by the PUSCH. Also, downlinkradio quality information (CQI: Channel Quality Indicator), deliveryacknowledgement information and so on are communicated by the PUCCH. Bymeans of the PRACH, random access preambles for establishing connectionswith cells are communicated.

In the radio communication systems 1, the cell-specific reference signal(CRS: Cell-specific Reference Signal), the channel state informationreference signal (CSI-RS: Channel State Information-Reference Signal),the demodulation reference signal (DMRS: DeModulation Reference Signal),the positioning reference signal (PRS) and so on are communicated as DLreference signals. Also, in the radio communication system 1, themeasurement reference signal (SRS: Sounding Reference Signal), thedemodulation reference signal (DMRS) and so on are communicated as ULreference signals. Note that the DMRS may be referred to as a “userterminal-specific reference signal (UE-specific Reference Signal).”Also, the reference signals to be communicated are by no means limitedto these.

<Radio Base Station>

FIG. 17 is a diagram to show an example of an overall structure of aradio base station according to the present embodiment. A radio basestation 10 has a plurality of transmitting/receiving antennas 101,amplifying sections 102, transmitting/receiving sections 103, a basebandsignal processing section 104, a call processing section 105 and acommunication path interface 106. Note that one or moretransmitting/receiving antennas 101, amplifying sections 102 andtransmitting/receiving sections 103 may be provided.

User data to be transmitted from the radio base station 10 to a userterminal 20 through DL is input from the higher station apparatus 30 tothe baseband signal processing section 104, via the communication pathinterface 106.

In the baseband signal processing section 104, the user data issubjected to a PDCP (Packet Data Convergence Protocol) layer process,user data division and coupling, RLC (Radio Link Control) layertransmission processes such as RLC retransmission control, MAC (MediumAccess Control) retransmission control (for example, an HARQ (HybridAutomatic Repeat reQuest) transmission process), scheduling, transportformat selection, channel coding, an inverse fast Fourier transform(IFFT) process and a precoding process, and the result is forwarded toeach transmitting/receiving section 103. Furthermore, DL control signalsare also subjected to transmission processes such as channel coding andan inverse fast Fourier transform, and forwarded to eachtransmitting/receiving section 103.

Baseband signals that are precoded and output from the baseband signalprocessing section 104 on a per antenna basis are converted into a radiofrequency band in the transmitting/receiving sections 103, and thentransmitted. The radio frequency signals having been subjected tofrequency conversion in the transmitting/receiving sections 103 areamplified in the amplifying sections 102, and transmitted from thetransmitting/receiving antennas 101. The transmitting/receiving sections103 can be constituted by transmitters/receivers, transmitting/receivingcircuits or transmitting/receiving apparatus that can be described basedon general understanding of the technical field to which the presentinvention pertains. Note that a transmitting/receiving section 103 maybe structured as a transmitting/receiving section in one entity, or maybe constituted by a transmitting section and a receiving section.

Meanwhile, as for UL signals, radio frequency signals that are receivedin the transmitting/receiving antennas 101 are each amplified in theamplifying sections 102. The transmitting/receiving sections 103 receivethe UL signals amplified in the amplifying sections 102. The receivedsignals are converted into the baseband signal through frequencyconversion in the transmitting/receiving sections 103 and output to thebaseband signal processing section 104.

In the baseband signal processing section 104, user data that isincluded in the UL signals that are input is subjected to a fast Fouriertransform (FFT) process, an inverse discrete Fourier transform (IDFT)process, error correction decoding, a MAC retransmission controlreceiving process, and RLC layer and PDCP layer receiving processes, andforwarded to the higher station apparatus 30 via the communication pathinterface 106. The call processing section 105 performs call processing(such as setting up and releasing communication channels), manages thestate of the radio base stations 10 and manages the radio resources.

The communication path interface section 106 transmits and receivessignals to and from the higher station apparatus 30 via a predeterminedinterface. Also, the communication path interface 106 may transmit andreceive signals (backhaul signaling) with other radio base stations 10via an inter-base station interface (which is, for example, opticalfiber that is in compliance with the CPRI (Common Public RadioInterface), the X2 interface, etc.).

Note that the transmitting/receiving sections 103 transmit DL signals(for example, DL control signals, DL data signals, DL reference signals,discovery signals, synchronization signals, broadcast signals, etc.) andreceive UL signals (for example, UL control signals, UL data signals, ULreference signals, random access preambles, etc.). To be more specific,the transmitting/receiving sections 103 transmit DL signals in DLfrequencies and receive UL signals in UL frequencies.

To be more specific, following commands from the control section 301,the transmitting/receiving sections 103 carry out the transmission of DLsignals (first aspect) and/or the receipt of UL signals (second aspect)in FDD, which use different frequencies, in the same timing as thetransmission of DL signals and/or the receipt of UL signals in TDD,which use the same frequency.

In addition, in at least one of a DL period, in which a DL data signaland a DL control signal that schedules this DL data signal aretransmitted using the DL frequency (first frequency), and a guard periodin TDD, the transmitting/receiving sections 103 may receive a UL datasignal and/or a UL sounding reference signal by using the UL frequency(second frequency) (third aspect).

In addition, in at least one of a UL period, in which a feedback signalin response to a DL data signal is received using the UL frequency, anda guard period in TDD, the transmitting/receiving sections 103 maytransmit a DL data signal and/or a DL sounding reference signal by usingthe DL frequency (third aspect).

In addition, in at least one of a DL period in which a DL control signalthat schedules a UL data signal is transmitted using the DL frequency,and a guard period in TDD, the transmitting/receiving sections 103 mayreceive a UL data signal and/or a UL sounding reference signal by usingthe UL frequency (third aspect).

In addition, in at least one of a UL period in which a UL data signal isreceived using the UL frequency, and a guard period in TDD, thetransmitting/receiving sections 103 may transmit a DL data signal and/ora DL sounding reference signal by using the DL frequency (third aspect).

FIG. 18 is a diagram to show an example of a functional structure of aradio base station according to the present embodiment. Note that,although FIG. 18 primarily shows functional blocks that pertain tocharacteristic parts of the present embodiment, the radio base station10 has other functional blocks that are necessary for radiocommunication as well. As shown in FIG. 18, the baseband signalprocessing section 104 at least has a control section (scheduler) 301, atransmission signal generation section 302, a mapping section 303, areceived signal processing section 304 and a measurement section 305.

The control section (scheduler) 301 controls the whole of the radio basestation 10. The control section 301 can be constituted by a controller,a control circuit or control apparatus that can be described based ongeneral understanding of the technical field to which the presentinvention pertains.

The control section 301, for example, controls the generation of signalsin the transmission signal generation section 302, the allocation ofsignals by the mapping section 303, and so on. Furthermore, the controlsection 301 controls the signal receiving processes in the receivedsignal processing section 304, the measurements of signals in themeasurement section 305, and so on.

The control section 301 controls the scheduling (for example, resourceallocation) of DL signals and/or UL signals. For example, the controlsection 301 may schedule DL signals (for example, discovery signals,synchronization signals, broadcast signals, and so on) and/or UL signals(for example, random access preambles, and so on) that are configured inadvance in fixed subframes (see FIG. 1 and FIG. 2). In addition, thecontrol section 301 may schedule DL signals (for example, DL-SRSs, DLdata signals, and so on) and/or UL signals (for example, UL-SRSs, ULdata signals, and so on) in dynamic subframes (see FIG. 1 and FIG. 2).

Furthermore, the control section 301 controls the transmission of DLsignals and/or the receipt of UL signals in FDD, which use differentfrequencies, to the same timing as the transmission of DL signals and/orthe receipt of UL signals in TDD, which use the same frequency.

Also, in at least one of a DL period, in which a DL data signal and a DLcontrol signal that schedules this DL data signal are transmitted usingthe DL frequency, and a guard period in TDD, the control section 301 mayschedule or configure a UL data signal and/or a UL sounding referencesignal, which are received by using the UL frequency, by using a DLcontrol signal that is transmitted in the same subframe as that of theDL data signal or in a preceding subframe, or by means of higher layersignaling (third aspect, see FIGS. 11A, 11B, 12A, 12B, and 12C).

Also, in at least one of a UL period, in which a feedback signal inresponse to a DL data signal is received using the UL frequency, and aguard period in TDD, the control section 301 may schedule or configure aDL data signal and/or a DL sounding reference signal, which aretransmitted by using the DL frequency, by using a DL control signal thatis transmitted in the same subframe as that of the DL data signal or ina preceding subframe, or by means of higher layer signaling (thirdaspect, see FIGS. 11A, 11B, 12A, 12B, and 12C).

Also, in at least one of a DL period, in which a DL control signal thatschedules a UL data signal is transmitted using the DL frequency, and aguard period in TDD, the control section 301 may schedule or configure aUL data signal and/or a UL sounding reference signal, which are receivedby using the UL frequency, by using a DL control signal that istransmitted in the same subframe as that of the UL data signal or in apreceding subframe, or by means of higher layer signaling, (thirdaspect, see FIGS. 13A, 13B, 14A, 14B, 15A, and 15B.

Furthermore, in at least one of a UL period in which a UL data signal isreceived using the UL frequency, and a guard period in TDD, the controlsection 301 may, by using a DL control signal that is transmitted in thesame subframe as that of the UL data signal or in a preceding subframe,or by means of higher layer signaling, schedule or configure a DL datasignal and/or a DL sounding reference signal, which are transmitted byusing the DL frequency (third aspect, see FIGS. 13A, 13B, 14A, 14B, 15A,and 15B).

The transmission signal generation section 302 generates DL signals (DLcontrol signals, DL data signals, DL reference signals and so on) basedon commands from the control section 301, and outputs these signals tothe mapping section 303. The transmission signal generation section 302can be constituted by a signal generator, a signal generating circuit orsignal generating apparatus that can be described based on generalunderstanding of the technical field to which the present inventionpertains.

The transmission signal generation section 302 generates DL controlsignals (for example, DL assignments) for reporting DL signal schedulinginformation, and DL control signals (for example, UL grants) forreporting UL signal scheduling information, based on commands from thecontrol section 301, for example. Also, the DL data signals aresubjected to the coding process, the modulation process and so on, byusing coding rates and modulation schemes that are determined based on,for example, channel state information (CSI) from each user terminal 20.

The mapping section 303 maps the DL signals generated in thetransmission signal generation section 302 to predetermined radioresources based on commands from the control section 301, and outputsthese to the transmitting/receiving sections 103. The mapping section303 can be constituted by a mapper, a mapping circuit or mappingapparatus that can be described based on general understanding of thetechnical field to which the present invention pertains.

The received signal processing section 304 performs receiving processes(for example, demapping, demodulation, decoding and so on) of receivedsignals that are input from the transmitting/receiving sections 103.Here, the received signals include, for example, UL signals transmittedfrom the user terminals 20 (UL control signals, UL data signals, ULreference signals and so on). For the received signal processing section304, a signal processor, a signal processing circuit or signalprocessing apparatus that can be described based on generalunderstanding of the technical field to which the present inventionpertains can be used.

The received signal processing section 304 outputs the decodedinformation acquired through the receiving processes to the controlsection 301. For example, when a feedback signal (for example, aHARQ-ACK) is received, this feedback signal is output to the controlsection 301. Also, the received signal processing section 304 outputsthe received signals, the signals after the receiving processes and soon, to the measurement section 305.

The measurement section 305 conducts measurements with respect to thereceived signals. The measurement section 305 can be constituted by ameasurer, a measurement circuit or measurement apparatus that can bedescribed based on general understanding of the technical field to whichthe present invention pertains.

The measurement section 305 may measure the received power (for example,the RSRP (Reference Signal Received Power)), the received quality (forexample, RSRQ (Reference Signal Received Quality)), channel states andso on of the received signals. The measurement results may be output tothe control section 301.

<User Terminal>

FIG. 19 is a diagram to show an example of an overall structure of auser terminal according to the present embodiment. A user terminal 20has a plurality of transmitting/receiving antennas 201, amplifyingsections 202, transmitting/receiving sections 203, a baseband signalprocessing section 204 and an application section 205. Note that one ormore transmitting/receiving antennas 201, amplifying sections 202 andtransmitting/receiving sections 203 may be provided.

Radio frequency signals that are received in the transmitting/receivingantennas 201 are amplified in the amplifying sections 202. Thetransmitting/receiving sections 203 receive the DL signals amplified inthe amplifying sections 202. The received signals are subjected tofrequency conversion and converted into the baseband signal in thetransmitting/receiving sections 203, and output to the baseband signalprocessing section 204. A transmitting/receiving section 203 can beconstituted by a transmitters/receiver, a transmitting/receiving circuitor transmitting/receiving apparatus that can be described based ongeneral understanding of the technical field to which the presentinvention pertains. Note that a transmitting/receiving section 203 maybe structured as a transmitting/receiving section in one entity, or maybe constituted by a transmitting section and a receiving section.

In the baseband signal processing section 204, the baseband signal thatis input is subjected to an FFT process, error correction decoding, aretransmission control receiving process, and so on. Downlink user datais forwarded to the application section 205. The application section 205performs processes related to higher layers above the physical layer andthe MAC layer, and so on. Furthermore, in the downlink data, broadcastinformation is also forwarded to the application section 205.

Meanwhile, uplink user data is input from the application section 205 tothe baseband signal processing section 204. The baseband signalprocessing section 204 performs a retransmission control transmissionprocess (for example, an HARQ transmission process), channel coding,precoding, a discrete Fourier transform (DFT) process, an IFFT processand so on, and the result is forwarded to the transmitting/receivingsection 203. Baseband signals that are output from the baseband signalprocessing section 204 are converted into a radio frequency band in thetransmitting/receiving sections 203 and transmitted. The radio frequencysignals that are subjected to frequency conversion in thetransmitting/receiving sections 203 are amplified in the amplifyingsections 202, and transmitted from the transmitting/receiving antennas201.

Note that the transmitting/receiving sections 203 receive DL signals(for example, DL control signals, DL data signals, DL reference signals,discovery signals, synchronization signals, broadcast signals, etc.),and transmit UL signals (for example, UL control signals, UL datasignals, UL reference signals, random access preambles, etc.). To bemore specific, the transmitting/receiving sections 203 receive DLsignals in DL frequencies and transmit UL signal in UL frequencies.

To be more specific, following commands from the control section 401,the transmitting/receiving sections 203 carry out the receipt of DLsignals (first aspect) and/or the transmission of UL signals (secondaspect) in FDD, which use different frequencies, in the same timing asthe receipt of DL signals and/or the transmission of UL signals in TDD,which use the same frequency.

In addition, in at least one of a DL period in which a DL data signaland a DL control signal that schedules this DL data signal aretransmitted using the DL frequency, and a guard period in TDD, thetransmitting/receiving sections 203 may transmit a UL data signal and/ora UL sounding reference signal by using the UL frequency (third aspect).

In addition, in at least one of a UL period in which a feedback signalin response to a DL data signal is received using the UL frequency, anda guard period in TDD, the transmitting/receiving sections 203 mayreceive a DL data signal and/or a DL sounding reference signal by usingthe DL frequency (third aspect).

In addition, in at least one of a DL period, in which a DL controlsignal that schedules a UL data signal is transmitted using the DLfrequency, and a guard period in TDD, the transmitting/receivingsections 203 may transmit a UL data signal and/or a UL soundingreference signal by using the UL frequency (third aspect).

In addition, in at least one of a UL period in which a UL data signal isreceived using the UL frequency, and a guard period in TDD, thetransmitting/receiving sections 203 may receive a DL data signal and/ora DL sounding reference signal by using the DL frequency (third aspect).

FIG. 20 is a diagram to show an example of a functional structure of auser terminal according to the present embodiment. Note that, althoughFIG. 20 primarily shows functional blocks that pertain to characteristicparts of the present embodiment, the user terminal 20 has otherfunctional blocks that are necessary for radio communication as well. Asshown in FIG. 20, the baseband signal processing section 204 provided inthe user terminal 20 at least has a control section 401, a transmissionsignal generation section 402, a mapping section 403, a received signalprocessing section 404 and a measurement section 405.

The control section 401 controls the whole of the user terminal 20. Forthe control section 401, a controller, a control circuit or controlapparatus that can be described based on general understanding of thetechnical field to which the present invention pertains can be used.

The control section 401, for example, controls the generation of signalsin the transmission signal generation section 402, the allocation ofsignals by the mapping section 403, and so on. Furthermore, the controlsection 401 controls the signal receiving processes in the receivedsignal processing section 404, the measurements of signals in themeasurement section 405, and so on.

The control section 401 acquires the DL control signals (signalstransmitted in the PDCCH/EPDCCH) and DL data signals (signalstransmitted in the PDSCH) transmitted from the radio base station 10,via the received signal processing section 404. The control section 401controls the generation of feedback signals (for example, HARQ-ACKsand/or the like), UL data signals and so on, based on whether or notretransmission control is necessary, decided in response to the DLcontrol signals and DL data signals, and so on.

The control section 401 controls the receipt of DL signals (for example,discovery signals, synchronization signals, broadcast signals, etc.)and/or the transmission of UL signals (for example, random accesspreambles), configured in advance in fixed subframes. Furthermore, thecontrol section 401 controls the receipt of DL signals and/or thetransmission of UL signals in dynamic subframes, dynamically orsemi-dynamically.

Furthermore, the control section 401 controls the receipt of DL signalsand/or the transmission of UL signals in FDD, which use differentfrequencies, to the same timing as the receipt of DL signals and/or thetransmission of UL signals in TDD, which use the same frequency.

For example, the control section 401 can control the receipt of a DLdata signal based on the DL control signal contained in the samesubframe as that of the DL data signal (FIGS. 6A, 6B, and 6C).Furthermore, the control section 401 may control a feedback signal inTDD, which is transmitted using the FDD UL frequency, to be transmittedin the same timing as a feedback signal in TDD (FIGS. 6A, 6B, and 6C).The feedback signal may be scheduled implicitly (FIG. 7A), or may bescheduled explicitly (FIG. 7B).

Furthermore, the control section 401 may control a UL data signal, whichis transmitted using the UL frequency, to be transmitted in the sametiming as a UL data signal in TDD, based on a DL control signal receivedin the FDD DL frequency. This UL data signal may be scheduled by the DLcontrol signal in the same subframe (FIGS. 8A and 8B), or may bescheduled by the DL control signal in a preceding subframe (FIGS. 9A and9B).

Also, in at least one of a DL period, in which a data signal and a DLcontrol signal that schedules this DL data signal are transmitted usingthe DL frequency, and a guard period in TDD, the control section 401 maycontrol the transmission of a UL data signal and/or a UL soundingreference signal, which uses the UL frequency, based on a DL controlsignal that is transmitted in the same subframe as that of the DL datasignal or in a preceding subframe, or based on higher layer signaling(third aspect, see FIGS. 11A, 11B, 12A, 12B, and 12C).

Also, in at least one of a UL period in which a feedback signal inresponse to a DL data signal is received using the UL frequency, and aguard period in TDD, the control section 401 may control the receipt ofa DL data signal and/or a DL sounding reference signal, which uses theDL frequency, based on a DL control signal that is transmitted in thesame subframe as that of the DL data signal or in a preceding subframe,or based on higher layer signaling (third aspect, see FIGS. 11A, 11B,12A, 12B, and 12C).

Also, in at least one of a DL period, in which a DL control signal thatschedules a UL data signal is transmitted using the DL frequency, and aguard period in TDD, the control section 401 may control thetransmission of a UL data signal and/or a UL sounding reference signal,which uses the UL frequency, based on the DL control signal transmittedin the same subframe as that of the UL data signal or in a precedingsubframe, or based on higher layer signaling (third aspect, see FIGS.13A, 13B, 14A, 14B, 15A, and 15B).

Furthermore, in at least one of a UL period in which a UL data signal isreceived using the UL frequency, and a guard period in TDD, the controlsection 401 may control the receipt of a DL data signal and/or a DLsounding reference signal, which uses the DL frequency, based on a DLcontrol signal that is transmitted in the same subframe as that of theUL data signal or in a preceding subframe, or based on higher layersignaling (third aspect, see FIGS. 13A, 13B, 14A, 14B, 15A, and 15B).

The transmission signal generation section 402 generates UL signals (ULcontrol signals, UL data signals, UL reference signals and so on) basedon commands from the control section 401, and outputs these signals tothe mapping section 403. The transmission signal generation section 402can be constituted by a signal generator, a signal generating circuit orsignal generating apparatus that can be described based on generalunderstanding of the technical field to which the present inventionpertains.

For example, the transmission signal generation section 402 generates ULcontrol signals related to delivery acknowledgement information, channelstate information (CSI) and so on, based on commands from the controlsection 401. Also, the transmission signal generation section 402generates UL data signals based on commands from the control section401. For example, when a UL grant is contained in a DL control signalthat is reported from the radio base station 10, the control section 401commands the transmission signal generation section 402 to generate a ULdata signal.

The mapping section 403 maps the UL signals generated in thetransmission signal generation section 402 to radio resources based oncommands from the control section 401, and output the result to thetransmitting/receiving sections 203. The mapping section 403 can beconstituted by a mapper, a mapping circuit or mapping apparatus that canbe described based on general understanding of the technical field towhich the present invention pertains.

The received signal processing section 404 performs receiving processes(for example, demapping, demodulation, decoding and so on) of receivedsignals that are input from the transmitting/receiving sections 203.Here, the received signals include, for example, DL signals (DL controlsignals, DL data signals, DL reference signals and so on) that aretransmitted from the radio base station 10. The received signalprocessing section 404 can be constituted by a signal processor, asignal processing circuit or signal processing apparatus that can bedescribed based on general understanding of the technical field to whichthe present invention pertains. Also, the received signal processingsection 404 can constitute the receiving section according to thepresent invention.

The received signal processing section 404 blind-decodes the DL controlsignals (DCI format) that schedules transmission and/or receipt of data(TBs: Transport Blocks), based on commands from the control section 401.For example, the received signal processing section 404 may beconfigured to blind-decode different radio resources based on whether ornot the subframes are self-contained subframes.

The received signal processing section 404 outputs the decodedinformation, acquired through the receiving processes, to the controlsection 401. The received signal processing section 404 outputs, forexample, broadcast information, system information, RRC signaling, DCIand so on, to the control section 401. The received signal processingsection 404 may output the decoding result of the data to the controlsection 401. Also, the received signal processing section 404 outputsthe received signals, the signals after the receiving processes and soon, to the measurement section 405.

The measurement section 405 conducts measurements with respect to thereceived signals. The measurement section 405 can be constituted by ameasurer, a measurement circuit or measurement apparatus that can bedescribed based on general understanding of the technical field to whichthe present invention pertains.

The measurement section 405 may measure, for example, the received power(for example, RSRP), the received quality (for example, RSRQ), thechannel states and so on of the received signals. The measurementresults may be output to the control section 401.

<Hardware Structure>

Note that the block diagrams that have been used to describe the aboveembodiments show blocks in functional units. These functional blocks(components) may be implemented in arbitrary combinations of hardwareand/or software. Also, the means for implementing each functional blockis not particularly limited. That is, each functional block may beimplemented with 1 piece of physically-integrated apparatus, or may beimplemented by connecting 2 physically-separate pieces of apparatus viaradio or wire and by using these multiple pieces of apparatus.

That is, a radio base station, a user terminal and so on according to anembodiment of the present invention may function as a computer thatexecutes the processes of the radio communication method of the presentinvention. FIG. 21 is a diagram to show an example of a hardwarestructure of a radio base station and a user terminal according to thepresent embodiment. Physically, the above-described radio base stations10 and user terminals 20 may be formed as a computer apparatus thatincludes a processor 1001, a memory 1002, a storage 1003, communicationapparatus 1004, input apparatus 1005, output apparatus 1006 and a bus1007.

Note that, in the following description, the word “apparatus” may bereplaced by “circuit,” “device,” “unit” and so on. Note that thehardware structure of a radio base station 10 and a user terminal 20 maybe designed to include one or more of each apparatus shown in thedrawings, or may be designed not to include part of the apparatus.

Each function of the radio base station 10 and the user terminal 20 isimplemented by reading predetermined software (program) on hardware suchas the processor 1001 and the memory 1002, and by controlling thecalculations in the processor 1001, the communication in thecommunication apparatus 1004, and the reading and/or writing of data inthe memory 1002 and the storage 1003.

The processor 1001 may control the whole computer by, for example,running an operating system. The processor 1001 may be configured with acentral processing unit (CPU), which includes interfaces with peripheralapparatus, control apparatus, computing apparatus, a register and so on.For example, the above-described baseband signal processing section 104(204), call processing section 105 and so on may be implemented by theprocessor 1001.

Furthermore, the processor 1001 reads programs (program codes), softwaremodules or data, from the storage 1003 and/or the communicationapparatus 1004, into the memory 1002, and executes various processesaccording to these. As for the programs, programs to allow computers toexecute at least part of the operations of the above-describedembodiments may be used. For example, the control section 401 of theuser terminals 20 may be implemented by control programs that are storedin the memory 1002 and that operate on the processor 1001, and otherfunctional blocks may be implemented likewise.

The memory 1002 is a computer-readable recording medium, and may beconstituted by, for example, at least one of a ROM (Read Only Memory),an EPROM (Erasable Programmable ROM), a RAM (Random Access Memory) andso on. The memory 1002 may be referred to as a “register,” a “cache,” a“main memory (primary storage apparatus)” and so on. The memory 1002 canstore executable programs (program codes), software modules and the likefor implementing the radio communication methods according to presentembodiment.

The storage 1003 is a computer-readable recording medium, and isconfigured with at least one of an optical disk such as a CD-ROM(Compact Disc ROM), a hard disk drive, a flexible disk, amagneto-optical disk, a flash memory and so on. The storage 1003 may bereferred to as “secondary storage apparatus.”

The communication apparatus 1004 is hardware (transmitting/receivingdevice) for allowing inter-computer communication by using wired and/orwireless networks, and may be referred to as, for example, a “networkdevice,” a “network controller,” a “network card,” a “communicationmodule” and so on. For example, the above-describedtransmitting/receiving antennas 101 (201), amplifying sections 102(202), transmitting/receiving sections 103 (203), communication pathinterface 106 and so on may be implemented by the communicationapparatus 1004.

The input apparatus 1005 is an input device for receiving input from theoutside (for example, a keyboard, a mouse, etc.). The output apparatus1006 is an output device for sending output to the outside (for example,a display, a speaker, etc.). Note that the input apparatus 1005 and theoutput apparatus 1006 may be provided in an integrated structure (forexample, a touch panel).

Furthermore, these types of apparatus, including the processor 1001, thememory 1002 and others, are connected by a bus 1007 for communicatinginformation. The bus 1007 may be formed with a single bus, or may beformed with buses that vary between pieces of apparatus.

Also, the radio base station 10 and the user terminal 20 may bestructured to include hardware such as a microprocessor, a digitalsignal processor (DSP), an ASIC (Application-Specific IntegratedCircuit), a PLD (Programmable Logic Device), an FPGA (Field ProgrammableGate Array) and so on, and part or all of the functional blocks may beimplemented by the hardware. For example, the processor 1001 may beimplemented with at least one of these pieces of hardware.

Note that the terminology used in this specification and the terminologythat is needed to understand this specification may be replaced by otherterms that convey the same or similar meanings. For example, “channels”and/or “symbols” may be replaced by “signals (or “signaling”).” Also,“signals” may be “messages.” Furthermore, a “component carrier” (CC) maybe referred to as a “cell,” a “frequency carrier,” a “carrier frequency”and so on.

Furthermore, a radio frame may be comprised of one or more periods(frames) in the time domain. Each of one or more periods (frames)constituting a radio frame may be referred to as a “subframe.”Furthermore, a subframe may be comprised of one or more slots in thetime domain. Furthermore, a slot may be comprised of 1 or multiplesymbols (OFDM symbols, SC-FDMA symbols, etc.) in the time domain.

A radio frame, a subframe, a slot and a symbol all represent the timeunit in signal communication. A radio frames, a subframe, a slot and asymbol may be each called by other applicable names. For example, onesubframe may be referred to as a “transmission time interval (TTI),” ora plurality of consecutive subframes may be referred to as a “TTI,” andone slot may be referred to as a “TTI.” That is, a subframe and a TTImay be a subframe (one ms) in existing LTE, may be a shorter period thanone ms (for example, one to thirteen symbols), or may be a longer periodof time than one ms.

Here, a TTI refers to the minimum time unit of scheduling in radiocommunication, for example. For example, in LTE systems, a radio basestation schedules the allocation of radio resources (such as thefrequency bandwidth and transmission power that can be used by each userterminal) for each user terminal in TTI units. Note that the definitionof TTIs is not limited to this.

A TTI having a time duration of one ms may be referred to as a “normalTTI (TTI in LTE Rel. 8 to 12),” a “long TTI,” a “normal subframe,” a“long subframe,” etc. A TTI that is shorter than a normal TTI may bereferred to as a “shortened TTI,” a “short TTI,” a “shortened subframe,”a “short subframe,” or the like.

A resource block (RB) is the unit of resource allocation in the timedomain and the frequency domain, and may include one or a plurality ofconsecutive subcarriers in the frequency domain. Also, an RB may includeone or more symbols in the time domain, and may be one slot, onesubframe or one TTI in length. One TTI and one subframe each may becomprised of one or more resource blocks. Note that an RB may bereferred to as a “physical resource block (PRB: Physical RB),” a “PRBpair,” an “RB pair,” or the like.

Furthermore, a resource block may be comprised of one or more resourceelements (REs). For example, one RE may be a radio resource field of onesubcarrier and one symbol.

Note that the above-described structures of radio frames, subframes,slots, symbols and so on are merely examples. For example,configurations such as the number of subframes included in a radioframe, the number of slots included in a subframe, the number of symbolsand RBs included in a slot, the number of subcarriers included in an RB,the number of symbols in a TTI, the symbol duration and the cyclicprefix (CP) length can be variously changed.

Also, the information and parameters described in this specification maybe represented in absolute values or in relative values with respect topredetermined values, or may be represented in other informationformats. For example, radio resources may be specified by predeterminedindices.

The information, signals and/or others described in this specificationmay be represented by using a variety of different technologies. Forexample, data, instructions, commands, information, signals, bits,symbols and chips, all of which may be referenced throughout theherein-contained description, may be represented by voltages, currents,electromagnetic waves, magnetic fields or particles, optical fields orphotons, or any combination of these.

Also, software, commands, information and so on may be transmitted andreceived via communication media. For example, when software istransmitted from a website, a server or other remote sources by usingwired technologies (coaxial cables, optical fiber cables, twisted-paircables, digital subscriber lines (DSL) and so on) and/or wirelesstechnologies (infrared radiation and microwaves), these wiredtechnologies and/or wireless technologies are also included in thedefinition of communication media.

Furthermore, the radio base stations in this specification may beinterpreted as user terminals. For example, each aspect/embodiment ofthe present invention may be applied to a configuration in whichcommunication between a radio base station and a user terminal isreplaced with communication among a plurality of user terminals (D2D:Device-to-Device). In this case, user terminals 20 may have thefunctions of the radio base stations 10 described above. In addition,wording such as “uplink” and “downlink” may be interpreted as “side.”For example, an uplink channel may be interpreted as a side channel.

Likewise, the user terminals in this specification may be interpreted asradio base stations. In this case, the radio base stations 10 may havethe functions of the user terminals 20 described above.

The aspects/embodiments illustrated in this specification may be usedindividually or in combinations, which may be switched depending on themode of implementation. Also, predetermined information (for example,reporting of information to the effect that “X holds”) does notnecessarily have to be reported explicitly, and can be reported in animplicit manner (by, for example, not reporting this piece ofinformation).

Reporting of information is by no means limited to theaspects/embodiments described in this specification, and other methodsmay be used as well. For example, reporting of information may beimplemented by using physical layer signaling (for example, DCI(Downlink Control Information) and UCI (Uplink Control Information)),higher layer signaling (for example, RRC (Radio Resource Control)signaling, broadcast information (the MIB (Master Information Blocks)and SIBs (System Information Blocks) and so on) and MAC (Medium AccessControl) signaling, other signals or combinations of these.

Also, RRC signaling may be referred to as “RRC messages,” and can be,for example, an RRC connection setup message, RRC connectionreconfiguration message, and so on. Also, MAC signaling may be reportedusing, for example, MAC control elements (MAC CEs (Control Elements)).

The aspects/embodiments illustrated in this specification may be appliedto LTE (Long Term Evolution), LTE-A (LTE-Advanced), LTE-B (LTE-Beyond),SUPER 3G, IMT-Advanced, 4G (4th generation mobile communication system),5G (5th generation mobile communication system), FRA (Future RadioAccess), New-RAT (Radio Access Technology), CDMA 2000, UMB (Ultra MobileBroadband), IEEE 802.11 (Wi-Fi (registered trademark)), IEEE 802.16(WiMAX (registered trademark)), IEEE 802.20, UWB (Ultra-WideB and),Bluetooth (registered trademark), systems that use other adequatesystems and/or next-generation systems that are enhanced based on these.

The order of processes, sequences, flowcharts and so on that have beenused to describe the aspects/embodiments herein may be re-ordered aslong as inconsistencies do not arise. For example, although variousmethods have been illustrated in this specification with variouscomponents of steps in exemplary orders, the specific orders that areillustrated herein are by no means limiting.

Now, although the present invention has been described in detail above,it should be obvious to a person skilled in the art that the presentinvention is by no means limited to the embodiments described herein.For example, the above-described embodiments may be used individually orin combinations. The present invention can be implemented with variouscorrections and in various modifications, without departing from thespirit and scope of the present invention defined by the recitations ofclaims. Consequently, the description herein is provided only for thepurpose of explaining examples, and should by no means be construed tolimit the present invention in any way.

1. A terminal comprising: a processor that, in case where frequencydivision duplex (FDD) is applied, controls a transmission of an uplink(UL) signal, in FDD, at a same timing as a UL transmission timing thatis applied in time division duplex (TDD); a receiver that receives adownlink control information (DCI), and a physical downlink sharedchannel (PDSCH) scheduled by the DCI; and a transmitter that transmits aHARQ-ACK in response to the PDSCH, wherein the reception of the DCI andthe transmission of the HARQ-ACK are allowed within one slot.
 2. Theterminal according to claim 1, wherein the receiver receives a downlink(DL) signal, and wherein the processor, when full duplex transmission isapplied, performs a control to transmit the UL signal even if a timesection for transmitting the UL signal overlaps a time section forreceiving the DL signal.
 3. A radio communication method for a terminalcomprising: controlling, in case where frequency division duplex (FDD)is applied, a transmission of an uplink (UL) signal, in FDD, at a sametiming as a UL transmission timing that is applied in time divisionduplex (TDD); receiving a downlink control information (DCI), and aphysical downlink shared channel (PDSCH) scheduled by the DCI; andtransmitting a HARQ-ACK in response to the PDSCH, wherein the receptionof the DCI and the transmission of the HARQ-ACK are allowed within oneslot.
 4. A base station comprising: a receiver that, in case wherefrequency division duplex (FDD) is applied, receives an uplink (UL)signal, in FDD, controlled at a same timing as a UL transmission timingthat is applied in time division duplex (TDD); a transmitter thattransmits a downlink control information (DCI), and a physical downlinkshared channel (PDSCH) scheduled by the DCI; and a processor thatcontrols a reception of a HARQ-ACK in response to the PDSCH, wherein thetransmission of the DCI and the reception of the HARQ-ACK are allowedwithin one slot.
 5. A system comprising a terminal and a base station,wherein: the terminal comprises: a processor that, in case wherefrequency division duplex (FDD) is applied, controls a transmission ofan uplink (UL) signal, in FDD, at a same timing as a UL transmissiontiming that is applied in time division duplex (TDD); a receiver thatreceives a downlink control information (DCI), and a physical downlinkshared channel (PDSCH) scheduled by the DCI; and a transmitter thattransmits a HARQ-ACK in response to the PDSCH, wherein the reception ofthe DCI and the transmission of the HARQ-ACK are allowed within oneslot, and the base station comprises: a receiver that receives the ULsignal and the HARQ-ACK.